Best Free game online in my opinion is War Thunder. Been around for sometime now but I still love playing it.

War Thunder is an free-to-play MMO combat simulator dedicated to mid-20th century military aviation, armored vehicles, and naval vessel combat. You will take part in all of the major combat battles, fighting with real players all over the world. Become a lone hero or lead your team to victory — the choice is yours! War Thunder offers:

Varied PvP full-scale combat missions
An experience for both advanced virtual pilots and beginners.
A co-op dynamic campaign, single-player missions, and a robust mission editor.
A variety of aircraft with detailed flight models, exteriors, and interiors.
Brilliant graphics, authentic sounds, and beautiful music.
Great simulation and realistic game play. You can upgrade if you want to achieve quicker, but I like to advance myself without paying anything.

What exactly do you interested in? I play PUBG on PC, great game, I recommend to try. If you want some online browser games check https://www.skywardgames.com/ this website. Here I like to play Angry Birds, very cool and popular games)